New York Agreement
The Bitcoin Scaling Agreement at Consensus 2017, better known as the New York Agreement (abbreviated NYA), was a scaling proposal made jointly by over 50 companies. The agreement intended to put an end to Bitcoin’s long-lasting scaling debate by increasing the block capacity through activating Segregated Witness and then doubling the block size.
The protocol change specification is given in PCS-0002. It is based on the "Segwit2Mb" thread on the bitcoin-dev mailing list and the NYA blog post.